1 Corinthians 13:12 offers a powerful statement about the limits of human knowledge. Paul's image of seeing dimly in a mirror suggests that our present understanding of reality is incomplete and imperfect. We can know genuine truths, but we do not see the whole picture. Full understanding belongs to the future, when we will see "face to face." The passage therefore encourages intellectual humility without falling into scepticism. Our knowledge is limited, but this does not mean that truth itself is uncertain or unreal. For Paul, moreover, the highest form of knowledge is not simply possessing facts or mastering arguments. Human knowledge ultimately finds its fulfilment in a direct relationship with God: "then I shall know fully, even as I am fully known." The limitation lies in the human knower, not necessarily in the reality being known. While all this seems abstract let me illustrate St. Paul's thesis with a discussion of the philosophical significance of dreaming.
Something rather strange happened to me in a dream recently. Strange things happening in dreams are hardly news, of course. What interested me was what happened next. Something within the dream became sufficiently absurd that I began to analyse it. I was still asleep and still apparently a character within the dream, yet I somehow stood back intellectually from what was occurring and concluded that it could not be real. I then reached the obvious explanation: I was dreaming. Almost instantaneously I woke up. It was as though recognising the illusion had broken the spell.
The experience brought to mind one of the oldest problems in modern philosophy: René Descartes' famous dream argument. Descartes asked how we can be absolutely certain that our present experiences are waking experiences rather than dreams. I presently believe that I am sitting at a table looking at a computer screen. But I have dreamed of sitting at tables, looking at things and speaking with people, and while dreaming I generally accepted those experiences as real. If dreams can seem real while we are having them, what absolutely certain test establishes that I am awake now?
The argument has troubled philosophers for centuries because there seems to be no infallible sensory mark separating the two. But my little experience suggests an interesting qualification. Sometimes a dream contains the evidence necessary to expose itself.
Dreams are often extraordinarily inconsistent. Places suddenly change. People become other people while somehow remaining themselves. Someone long dead appears and we accept his presence without surprise. Journeys occur without the intervening journey. Causal sequences collapse. Time and space behave in ways that would immediately alarm us in waking life. Usually, the dreaming mind simply accepts all of this.
Occasionally, however, something different happens. The critical faculties appear to come back online. The dreamer notices the contradiction. Instead of merely participating in the dream, he begins reasoning about the world being presented to him. Something like the following inference occurs: this event cannot fit coherently into the world as I understand it; nevertheless I am experiencing it; therefore perhaps this experienced world is not waking reality at all. I am dreaming.
This phenomenon is associated with lucid dreaming, in which a person becomes aware while still asleep that he is dreaming. What makes it philosophically interesting is that the discovery can apparently be made from within the dream. The dreamer does not necessarily need to wake up, examine the external world and retrospectively declare the earlier experience false. The dream itself may contain contradictions sufficient to undermine its own claim upon belief.
This gives us a modest weapon against an excessively strong version of Cartesian scepticism. It cannot be true that nothing available within a dream could ever provide evidence that one is dreaming. Sometimes there is such evidence, and sometimes the dreaming person actually recognises it.
But Descartes is not so easily defeated. Imagine a perfectly coherent dream. I dream that I awaken in my usual surroundings, get dressed, eat breakfast, go to work, speak with familiar people, spend the day writing, return home and eventually go to sleep. Nothing miraculous happens. Physical objects behave normally. Memories remain consistent. Clocks agree with one another. Other people respond appropriately. Every causal relationship behaves exactly as I expect.
What contradiction could expose that dream? Perhaps none. This produces an important asymmetry. Inconsistency may give me positive reason to conclude that I am dreaming, but consistency cannot prove that I am awake. A sufficiently coherent dream could reproduce the regularities of waking experience.
Modern technology gives the old Cartesian problem a new vocabulary. Instead of imagining an extraordinarily convincing dream, philosophers sometimes imagine a perfectly constructed computer simulation. If every experiment performed within the simulation produced precisely the result that would have occurred in the external world, inhabitants of the simulation might have no internal experiment capable of discovering their situation. The example is useful as a philosophical device, although there is no need to suppose that we actually inhabit such a simulation. In fact, there is simply no evidence for it at all.
The important point concerns knowledge rather than reality. Suppose we have two hypotheses. According to the first, I am awake and interacting with an objective world possessing stable causal regularities. According to the second, I am dreaming, but my dream perfectly reproduces every regularity that I would encounter if I were awake. Whenever I devise another test, the second hypothesis simply stipulates that I dream the appropriate result.
The second possibility cannot be eliminated with absolute logical certainty. But that does not put the two possibilities on equal intellectual footing. A hypothesis constructed so that nothing could possibly count against it has not thereby acquired powerful evidence in its favour. We can always manufacture sceptical possibilities of this kind. Perhaps the universe came into existence five minutes ago complete with all our memories. Perhaps an invisible deceiver manipulates every scientific instrument at precisely the right moment. Perhaps every historical document was fabricated yesterday. That speculation can go on even after the cows come home.
None of these possibilities can necessarily be disproved with Cartesian certainty. But logical possibility is not the same thing as evidential probability. From the fact that I cannot absolutely prove that I am not dreaming, it does not follow that I have no rational grounds for believing that I am awake.
There is also no need to take the argument in an anti-religious direction. Quite the contrary. Nothing about epistemic limitation requires us to conclude that reality itself is an illusion. That would confuse an argument about what human beings can know with an argument about what actually exists.
For the Christian, there need be no particular difficulty here. Creation can be objectively real even though finite creatures apprehend it imperfectly. Indeed, Christianity has never depended upon the proposition that unaided human cognition provides a God's-eye view of reality. Human beings are creatures situated within creation, not observers standing outside it.
St Paul captured something of this limitation in his famous words that "now we see through a glass, darkly." The theological context is obviously different from Descartes' epistemology, and the biblical passage should not be turned into a modern philosophy textbook. Nevertheless, the underlying reminder is relevant: incomplete human knowledge does not entail the absence of truth. It entails the limitation of the knower.
That distinction is crucial. There is an enormous difference between saying that objective reality does not exist and saying that human beings cannot obtain absolute certainty that their representations correspond perfectly with it. The first is an ontological (existence) claim. The second is an epistemological (knowledge) one.
The dream experience illustrates the difference beautifully. While dreaming, consciousness constructs an experienced world and presents it as reality. Normally the dreamer accepts the presentation. But occasionally reason turns upon the very world being presented to it. The dream effectively says: this is happening. The reasoning mind answers: no, something is wrong here. These events cannot coherently belong to the reality I know. The hypothesis that I am dreaming explains the contradiction.
Then the spell breaks. There is something remarkable about this. A cognitive system situated within a phenomenal world becomes capable of criticising that world. It does not escape experience altogether. It instead discovers an inconsistency within experience and uses reason to infer that appearances are misleading.
Yet reason cannot complete the escape from uncertainty. If the dream contained no detectable contradiction, the same procedure might fail. Internal coherence can expose some false representations, but coherence alone cannot guarantee correspondence between representation and external reality.
Descartes therefore survives, but his victory should be considerably reduced. His dream argument does not establish that waking and dreaming are equally credible. It does not establish that the external world is unreal. It certainly does not establish that truth itself is inaccessible. What it demonstrates is something more modest and, perhaps, more important: there are limits to the certainty obtainable by a finite knower situated within experience.
That conclusion should hardly terrify the Christian. If anything, the strange thing would be to expect otherwise. Christianity begins with a distinction between Creator and creature. We are not omniscient observers surveying reality from nowhere. We reason from within creation using limited senses, limited memories and limited intellectual capacities. That these faculties do not provide absolute Cartesian certainty is hardly surprising.
Nor does fallibility entail futility. A compass need not possess infinite precision to point north. Human knowledge can be genuine without being exhaustive, and rational belief can be justified without being incorrigible.
Perhaps that is the deeper lesson of the lucid dream. When the dream became sufficiently inconsistent, reason recognised the deception and I awoke. The experience shows that reason can sometimes break the spell of appearance. Descartes reminds us that there may be perfectly coherent appearances whose falsity we cannot demonstrate from within them.
The proper conclusion is therefore neither nihilism nor radical scepticism. It is epistemic humility. Reality need not be doubted merely because our access to it is imperfect. For the Christian, one might put the point more simply still: the limits of human knowledge are not necessarily limits upon reality or truth. They may simply be the limits one should expect of creatures who are not God.